﻿#define _CRT_SECURE_NO_WARNINGS 1

//编程初学者入门训练第三十三题
//BC35 判断字母
//https://www.nowcoder.com/practice/44d2d63103664913bc243d3836b4f341?tpId=107&tqId=33316&rp=1&ru=/exam/oj/ta&qru=/exam/oj/ta&sourceUrl=%2Fexam%2Foj%2Fta%3FtpId%3D107&difficulty=undefined&judgeStatus=undefined&tags=&title=

#include <stdio.h>

int main() {
    char ch;
    ch = getchar();
    if (ch >= 'a' && ch <= 'z' || ch >= 'A' && ch <= 'Z')
    {
        printf("YES");
    }
    else
    {
        printf("NO");
    }
    return 0;
}